1. Field of the Invention
The present invention relates generally to a fan frame body structure, and more particularly to a series fan frame body structure made of different materials. The vibration frequencies of the fan frames of the series fan are different from each other so that the co-vibration of the fan is reduced to lower the noise.
2. Description of the Related Art
The materials of the existent fan frames can be generally classified into two types, that is, metal frame body made by means of casting and plastic frame body made by means of injection molding. The cast metal frame body such as aluminum-made frame body has a higher price due to higher material cost. The plastic frame body made by means of injection molding, such as PBT, PA66 and PPE frame body has a much cheaper price than the metal frame body due to lower material cost so that the plastic frame body is popularly used in this field.
The forms of the current fans include one-fan form and series fan form. The fan in the one-fan form has a frame body simply made of plastic material such as PBT, PA66 or PPE. The series fan has two frame bodies serially connected with each other. The frame bodies are made of the same material of the same composition. For example, both frame bodies are made of PBT, PA66 or PPE.
No matter which form the fan has, the material and composition of the frame bodies are the same. Therefore, in the case that in operation of the fan, the excited frequency of the fan is close to the natural frequency of the fan frame, the fan will severely co-vibrate to make noise. This will ill affect the components of the fan to deteriorate the reading efficiency of hard disc of the system. Moreover, the lifetime of the system and the fan will be shortened.
It is therefore tried by the applicant to provide a series fan frame body structure made of different materials to solve the problem of co-vibration of the fan.